Emulsion paint



United States Patent ice EMULSION PAINT Ralph Sterling Armstrong, EastChicago, Ind., assignor to The Sherwin-Williams Company, Cleveland,Ohio, a corporation of Ohio No Drawing. Application December 14, 1953,

Serial No. 398,228

18 Claims. (Cl. 106-170) This invention relates to a nonionic emulsionpaint suitable for direct application to wall areas without furtherreduction with water and which has the capacity to tolerate inorganicionic material.

Heretofore, emulsion coating compositions applicable by brush to surfaceareas have been opacified with pigments selected for their freedom fromionizable metallic salts which salts contribute materially to the ioncontent of the emulsion system.

In the main, the commercially successful emulsion coatings containing anoleoresinous varnish as the disperse phase have relied upon the additionof long chain fatty acid soaps, rosin soaps, or anionic surface activeagents of the alkyl aryl sulfonate class, or the formation of soaps dueto residual acidity in the oleoresinous varnish for emulsification. Theaforementioned monomeric anionically classified surface active agentsare used alone and in combination with monionic agents, but in suchcases emulsion stability of the paint system is seriously impaired whenthe pigmentary phase, or the surface active agent carries with itionizable metal salts.

Further, while not uniquely so, the protective colloid useful in asystem based upon anionically active agents is most generally an aqueousdispersion of a protein, said dispersion achieved by employing therewithorganic and inorganic bases. The alkaline material necessary for thedispersion of the protein also contributes objectionable ions to theprior art oil-in-water emulsion paint systems. Further, emulsion paintsystems based upon salts of alkyl aryl sulfonates, soaps, etc., as thesurface active agents and stabilized with protein dispersions arecharacterized by pHs of 8 to 11 and preferably from about 8.5 to 9.0. ApH or hydrogen ion concentration in this range is essential to emulsionstability of such systems.

Perhaps the most serious limitation of prior-art emulsion coatingcompositions is their lack of tolerance of ionizable metal salts whichare present in many pigments either as an impurity from theirmanufacture or by deliberate inclusion as a component of the pigmentarymaterial of the disperse pigment phase. Most notable of these arepigments containing calcium sulfate, and particularly a compositepigment used extensively in conventional (as opposed to emulsion)coating compositions containing approximately 30 percent of titaniumdioxide and 70 percent of calcium sulfate, often referred to astitanium-calcium pigments. When one attempts to formulate an emulsioncoating using titanium-calcium piginents or pigments carrying anyappreciable amount, as little as 1-2 percent, of ionizable salt, theresults heretofore have been to produce a product incapable ofapplication by brush to sizeable wall areas, as in painting a room.While small test panels may be occasionally coated with such products,upon attempting to coat areas of practical dimension (e. g., a series of4 x 4' panels) the emulsion system breaks down and the emulsion paintgums in the brush, resulting in fine to coarse particles appearing overthe freshly coated wall area. Color uni- 2,778,740 Patented Jan. 22,1957 formity and opacity of the film are lost due to emulsion breakdown,and the area coated presents a most unsatisfactory aspect, a source ofconsumer complaint.

It is, therefore, an object of this invention to produce anemulsion-type coating composition capable of tolerating appreciablequantities of ionizable metal salts.

It is a further object to produce an emulsion paint capable of beingappliedto areas of practical dimension by means of brushing withoutemulsion breakdown, of essentially neutral pH or hydrogen ionconcentration.

It is a specific object to provide a pigmented emulsion in a conditionready for use, yet capable of being subject to repeated freezing andthawing cycles without emulsion breakdown.

Another specific object is to provide a pigmented emulsion for coatingpurposes containing only nonionic' surface active agents of a particularcategory as the emulsifying agent and water soluble cellulosic materialas the protective colloidal agent.

A further specific object is to provide a protein-free emulsion coatingcharacterized by its constant viscosity and freedom from odors ofpartial decomposition of proteins.

This application is a continuation-in-part of my copending applicationU. S. Serial No. 249,417 filed October 2, 1951, now abandoned.

The coating compositions of this invention consist of a disperse oilphase, a continuous aqueous phase and a solid pigmentary phase, the oilphase thereof comprising an oleoresinous varnish substantially free ofvolatile organic solvents and non-neutralized or non-esterfied acidity,the aqueous or continuous phase free from water souble monomeric organicsalts and soaps having surface activity (e. g., effect upon surfacetension) and containing as the two essential components thereof, atleast one monionic surface active agent and a water soluble cellulosederivative selected from the group consisting of methyl cellulose, ethylcellulose, hydroxyethyl cellulose and the ammonium and alkali metalsalts of carboxy methyl cellulose and cellulose sulfate as theprotective colloid. The aqueous phase constitutes in excess of 60percent by volume of the total composition and the emulsion coatingcomposition of this invention is characterized by a substantiallyneutral pH, low electrical conductivity prior to the incorporation ofpigments containing ionizable metal salts, and with or without inclusionof .ionizable calcium salts in the pigmentary phase, excellent emulsionstability.

THE DISPERSE OIL PHASE Considerable latitude exists in the selection ofthe oleoresinous varnish suitable as the oil phase of the disclosedcoating compositions. The nature of the oil phase is not critical andalmost all varnish vehicles can be employed for the purposes of thisinvention provided the acid value of the vehicle is not so high as toform objectionable quantities of soap in the presence of alkalinematerials. Acid values below 20 are preferred for this reason.

The term oleoresinous varnish is used herein as defined by M-attiello(vol. I, page 29) Protective and Decorative Coatings, e. g., a solutionor dispersion of a synthetic or natural resin in an (drying) oilvehicle. A chemical combination may or may not take place between theresin and oil in the cooking process. Later in vol. 3 of the samereference work, page 194, varnish is described as a liquid coatingmaterial containing no pigment which flows out to a smooth coat whenapplied and dries to a smooth, glossy, relatively hard, permanent solidwhen exposed in a thin film to air. On page of the same article anoleoresinous varnish is defined to include:

( 1) Oil plus:

(a) Natural resin (b) Synthetic resin (2) Oil (3) Oil modified glycerophthalate The proportions of resin to oil are somewhat limited byviscosity considerations for the smaller the amount of the oil, or theshorter the oil length (usually stated in terms of the number of gallonsof said oil to 100 pounds of resin) the greater the viscosity of theresultant varnish solids. As the viscosity of the varnish solids isincreased, the difn'cultics of handling and dispersion from a mechanicalview become more complex. Difficulty can be alleviated partially byheating, but at temperatures much above the boiling point ofwateradditional difficulties arise. For this reason, as well asconsiderations relative to the nature of the resultant film, it ispreferred to use a to gallon length varnish. In the case of alkydtypeoleoresinous varnishes, the percentage of dibasic acid, usually phthalicbut not essentially so, cannot be conveniently employed in excess of 25percent based on the total'weight of the alkyd vehicle solids.

Varnish vehicles useful in my compositions are substantially free ofvolatile organic solvents therefore. By substantially free is meant notgreater than 10 percent and preferably from 5 percent or less of solventmay be included. The preferred solvents in the limited range are thevolatile terpenes, such as d-limonene and the orange terpenes havingpleasant odor characteristics. Pine oil may be employed. Greater amountsof solvent are not desired as ordinary varnish solvents introduceobnoxious odor and reduce the vehicle solids content or the film-formingsolids of the emulsion system. Drying oils suitable as the oilconstituent may be conjugated oils or non-conjugated oils having aniodine value in excess of 120, soya bean oil being included within the ITHE AQUEOUS PHASE The aqueous phase of the emulsion coating compositiondescribed and claimed herein contains two essential components. Theseare a nonionic surface active agent or agents and a protective colloid.Attention is hereinafter directed to negative limitations and then toessential components of the phase.

While a number of nonionic emulsifying agents can be employed and arewithin the scope of the general disclosure, paints made without carefulselection among the broad class of nonionic surface active agents may belacking in one or more of the qualities of brushability, flow,reco'atability and washability obtained in the preferred embodiment ofmy invention as hereinafter more specifically disclosed.

As is well known in the art pertaining to surface active agents, thereare three principal classifications, the names of which are derived fromtheir functional behavior. These'classifications are anionic, nonionicand cationic by name. The anionic group constitutes the largest classand includes those of greatest variety in chemical structure.

Among the anionic class are the alkaline soaps or salts of acidicorganic compounds containing at least 8 carbon atoms in the lipophilicor oil loving portion of the molecule. Also included are most of thecompounds referred to broadly today as synthetic detergents which arecharacterized by solubility of their hard water salts or soaps. Thisclassification of surface active agents has been employed almostexclusively until recently in emulsion paint technology because of itsavailability, moderate price and effective performance.

Their presence in the composition here of interest cannot be tolerated,however, in appreciable amounts. Virtual absence of monomeric organicsoaps or salts (anionic surface active agents) heretofore employed inemulsion paint systems either by design or accident is the key to thesuccess of the combination herein described.

In setting forth the best method of practice of the invention, thenegative limitation is inherent. Yet the knowledge of the diiiiculty dueto the presence of ionic organic materials may be of material value tothose who Wish to practice the invention.

The cationic class of surface active agents is also of negative valueand serves no useful purpose and is presumed to be detrimental in theherein described composition.

Having described the classes of surface active agents to be avoided, theessential nonionic surface active agents will be considered.

The nonionic surface active agents essential to the ends of theinvention include compounds variously labeled as polyalcohol esters,polyglycol esters, polymerized higher glycol esters, polyhydric alcoholesters, polyalkyl ether esters, polyoxyalkylene esters, polyoxyethyleneesters, polyethylene glycol esters, alkyl aryl polyoxyethylene ethanols,alkyl polyoxyethylene ethanols, alkyl aryl polyoxypropylene ethanols,etc.

The polyhydric alcohol esters, by way of illustration, may bemonoglycerides of a long chain fatty acid, e. g. stearic, etc.,condensed with ethylene oxide, propylene oxide or mixtures thereof.

Other than a polyhydric alcohol, the water soluble portion or group ofthe molecule contains a plurality of ether linkages as obtained bycondensing therewith a plurality of alkylene oxide units. Ethylene oxideis the most often used but propylene oxide is not excluded and may besubstituted therefor in whole or in part in some instances.

Alkylene oxide condensates with polyhydric alcohols, etc., give rise toether alcohols, the nature of which depends in part upon the nature ofthe organic compound with which the alkylene oxide is condensed. Boththe ether linkage and the hydroxyl group contribute to the hydrophilicportion of the surface active molecule.

Alkylene oxides may also be condensed with water insoluble amines,phenols, etc. to increase the water sensitivity of the parent compoundto create nonionic agents useful for the purposes of this invention.

In the general art of surface active agents it has been fairly wellestablished that the oilophilic portion of the surface active agentmolecule will contain a minimum of eight carbon atoms. Often times alarger number of carbon atoms may be utilized, particularly where theoilophilic group is of the alkyl aryl classification or where theoilophilic group is derived from vegetable seed oils, petroleumderivatives, etc.

From the above it can be seen that small molecules having oil solubleand water soluble groups do not necessarily qualify as surface activeagents, as the term is generally employed in the emulsion art. Ethyleneglycol monoethyl ether, for example, is both oil soluble and watersoluble but does not qualify for the purposes of this invention. First,it is of too low a molecular weight. Second, the oilophilic portion ofthe molecule is of insuflicient size to be eifective as a detergentmaterial.

Trade names of nonionic surface active agents useful for the purposes ofthis invention include but are not limited to the following: r

Igepal CA Igepal #300 Igepal CO Antarox A-400 (C2H4O)10OH1OH:OH

Triton X-l00 Emulphor DDT Tween 20sorbitan monolaurate polyoxyethylenecondensate Ween 40sorbitan monopalmitate polyoxyethylene condensateTween 60sorbitan monostearate polyoxyethylene condensate Tween80-sorbitan monooleate polyoxyethylene condensate Antara 424one thirdmethyl alcoh0ltwo thirds of the condensation product of nonyl phenolwith about mols of ethylene oxide (Triton X-100) Ethomeen C/20(C2H2O)12CH2CHOH (Ca r0)1o0HrCH2OH where R is a coconut fatty acidgroup, etc.

The above trade named compounds include octyl and nonyl phenoxypolyoxyethylene ethanols wherein the ethanoxy' groups number from 7 to20, alkyl polyoxyalkylene ethanols wherein the alkyl group is a Ca andabove hydrocarbon and the polyoxyalkylene portion of the molecule isselected from the group consisting of ethylene and propylene oxideadducts. Others are produced from monoesters of polyhydric alcoholsfurther condensed with ethylene oxide and/ or propylene oxide whereinthe esterifying acid may be palmitic acid, stearic acid, oleic acid,etc. having at least 8 carbon atoms (preferably higher for the purposesof this invention), and long chain fatty (acid) amines condensed with aplurality of ethylene oxide or propylene oxide units.

In general, description of methods for producing nonionic surface activeagents of particular interest are de scribed more fully in U. S. Patent1,970,578 of August 21, 1934, now a part of the public domain.

The nonionic surface active detergents useful for the purposes of thisinvention include the water insoluble esters, ethers, amines and amidesof a nonomeric organic compound containing a hydrophobic group of atleast eight carbon atoms (and preferably larger, e. g. 12-20 carbonatoms) condensed with a sufficient number of alkylene oxide groups toform a hydrophilic polyether portion of the molecule, the resultantwater soluble nonionic agent having a molecular weight of not less than550. The preferred alkylene oxide is ethylene oxide, how ever aspreviously indicated, propylene oxide is known to be more or less usefulsubstituent therefor;

Of further importance in the nonionic surface active agent is thebalance between the hydrophobic portion and the hydrophilic portion ofthe molecule. So far as is known there is no art recognized method ofreducing this factor to a mathematical concept. There appears to be somerelationship in this balance to the solubility of the agent in water andin oil but solubility alone is merely indicative. If all surface activeagents were to be classified into five groups in order of increasinghydrophilic quality of the first would be of over-balanced oilophiliccharacteristic sufficiently to be water insoluble and to form onlywater-in-oil type emulsions, the second class would be useful primarilyfor wetting-out purposes, the third class as useful in producingoil-in-water emulsions, the fourth as detergents and the fifth assolubilizing agents. Nonionics having the proper hydrophilic-hydrophobicbalance for the present purposes would be classed under the fourthgroup, or as detergents as to this balance factor. Broadly, they maytherefore be classed as nonionic detergents. Addition of as little as0.5% of the useful nonionic agents of value here will reduce the surfacetension of distilled water from about 72 dynes to about 40 dynes.

Roughly, comparison of the molecular weight of the hydrophilic groups ofthe useful detergent class of nonionics to the molecular weight of thehydrophobic and oilophilic (oil soluble) groups indicates the usefulratio to be within the range of 1.5 to 1 to not appreciably above 3 to1.

An ancillary surface active agent has been found useful to enhance theworking properties, particularly the brushability of the emulsion paintsdescribed herein. This ancillary agent is defined herein as thecondensation product of a long chain fatty acid (e. g. 8-24 carbonatoms) with at least two mols of an alkylolamine at a temperature offrom to 300 C. Ninol 2012-A (a product of Ninol Laboratories, Chicago,Illinois, described in U. S. Patent 2,089,212 issued August 10, 1937.See also Reissue Patent No. 21,530) is illustrative of a usefulancillary nonionic agent. Doubtless other supplementary nonionic agentsmay be used for ancillary purposes in conjunction With the particularnonionics described as essential to the ends of this invention.

The second essential component of the aqueous phase is the protectivecolloid which, as the name implies, augments the stability of theemulsion system so that it can be stored under a variety of temperatureconditions and be applied over a variety of surfaces by one or moremethods of application, e. g., brushing, spraying, rollercoater, etc.,without disruption of the emulsion phase relationships. Heretofore,aqueous alkaline dispersions of proteins have been most commonly used.for this purpose, and heavy concentrations of long chain fatty acid androsin acid soaps have also served this purpose, but, as previouslystated, anionic agents are not useful nor operative for the purposes ofthis invention.

\ Suitable protective colloids for purposes of this invention includewater soluble cellulose derivatives selected from the group consistingof methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, andammonium and alkali metal salts of carboxymethyl cellulose and cellulosesulfate. These water soluble cellulose derivatives are not equallyuseful, although all may be used with a modicum of success. The alkalimetal salts of carboxymethyl cellulose are preferred, however, as thecombined effect of this class with the other preferred ingredients ofthe aqueous phase produces a totality of qualities of optimum valueamong emulsion coating compositions of the class herein described foruse in home decoration.

Water soluble methyl cellulose is the water soluble methoxy cellulosecompounds having between 1.2 to 1.9 methoxy groups per anhydroglucoseunit depending in some measure, of course, upon the degradation of thecellulose prior to etherification.

Water soluble ethyl cellulose as used herein, is a water soluble ethylcellulose containing in excess of 0.8 ethoxy groups to about 1.3 ethoxygroups per anhydroglucose unit-again depending upon the degradation ofthe cellulose.

Water soluble hydroxyethyl cellulose as used herein is a water solublehydroxyethyl cellulose containing an aver- 7 age of about 2.5 mols ofhydroxyethyl groups per anhydroglucose residue unit (CsHm'O5)z. Thevalue of z is not known with exactitude but is believed to be not lessthan .1000 nor more than about 2000 anhydroglucose units.

Water soluble carboxymethyl cellulose is the reaction product of analkali cellulose with monochloro-acetie acid containing from about 0.3to about 0.8 carboxy methyl groups per anhydroglucose unit in thepolymeric cellulose molecule. The water soluble salts of carboxymethylcellulose are formed by reaction of the carboxy group with the fixed andthe volatile alkalis to form the sodium, potassium, ammonium and relatedamine salts. The medium viscosity is the most useful of the commerciallyavailable carboxymethyl cellulose salts. The water soluble cellulosederivatives described and defined above are noted for their physicalcapacity to form gels in water at low solids concentrations.

By the term cellulose sulfate is meant a compound wherein approximatelyone sulfate group is attached per three anhydroglucose units of acellulose chain by estertype linkages, and again the sodium salt ispreferred although the other water soluble alnaline salts, as aboveindicated, are potential substitutes. The quantities of these materialsuseful is never suficient to reduce the aqueous phase to a paste ornon-fluid condition.

THE PIGMENTARY PHASE The distinct advance in the art of emulsion coatingcomposition in relation to the disclosed combination resides in thecapacity of the system to tolerate pigments containing from residual tovery considerable quantities of ionizable inorganic salts. The immediatepractical advantage is the ability to formulate emulsion coatingcompositions with titanium-calcium pigments which contain approximately70 percent of calcium sulfate by weight without breakdown of theemulsion paint, particularly upon application by brush which is one ofthe most severe of tests, particularly upon areas of commerciallysignificant size.

Another practical advance lies in the ability to use commerciallyavailable prime (or pigments promoting opacity in a paint system) andinert (or pigments of little hiding quality or opacity in the system)pigments containing residual quantities of ionizable metal salts, notably alkali and alkaline earth metal sulfates.

Prime pigments useful in the disclosed composition include titaniumdioxide, titanium dioxide-barium sulfate, titanium dioxide-calciumsulfate, zinc sulfide, lithopone (zinc sulfide-barium sulfate) andcombinations thereof. Advantage resides particularly in the ability ofthe emulsion system to tolerate calcium sulfate.

inert pigments useful include calcium carbonate, mica, talc,diatomaceous silica, colloidal silica, silica, pyrophyllite, etc. Arather wide selection among inerts is possible, particularly in mycomposition, for the reasons given above. inerts are not essential butare generally included in paints having other than a glossy finish orsurface. Surface treated titanium dioxide pigments inay be employed toproduce lossy emulsion enamels in those cases where the pigmentary phaseis dispersed in the oleoresinous varnish phase in the final paint film,but in fiat to high sheen coatings, the pigment will be generallydispersed in the aqueous phase.

The following examples will make clear the practice of manufacture ofthe above-described composition and the preferred embodiment thereof.

Example I 2250 pounds of varnish makers linseed oil (alkali refinedlinseed oil) were heated to 300 degrees F. and 750 pounds ofpentaerythritol ester of a maleic rosin adduct resin were added to thehot oil. Temperature was increased to between 550 to 600 degrees F. andheld for a body of from 6 to 8 minutes in 21 Gardner tube. The

or OD resulting varnish had a cure of '51 seconds, color'of l0. and anacid value of from 10 to 20 at 100 percent solids. Optionally, 5 percentby weight of d-limonene or pine oil may be added to the above varnishsolids.

Example II.Matte quality emulsion .paint Lbs. per Percent 100 Gals.Material by Volume Titantium-oalcium pigment (30% Tim-% Gas 04 4. 0Titanium dioxide pigment '6. 0 Lorite (lnert pigment) (Diatomaceousearth- CaO 0a 1. 5

The pigmentary materials, sodium cellulose glycolate, and the nonionicemulsifying agents are weighed into a pony mixer pan and 165 pounds ofwater are added thereto. The resulting stifi paste is allowed to mix for15 to 20 minutes after which the anti-foam agent is blended in. Thecobalt and lead driers are mixed with the varnish and the preparedvarnish vehicle is added slowly to the paste, which is again mixed foranother 15 to 20 minutes. An additional 165 pounds of water are added tothe resultant mixture and the entire contents of the pony mill pan arepassed through a colloid mill, set so that the clearance between therotor and stator is approximately 0.005 to 0.007 of an inch. Thereafterthe remaining water is added to the milled paste or sufiicient of it asis necessary to bring the viscosity of the resultant product to apredetermined good brushing level, e. g., 9 to 11 seconds onSherwin-Williams viscosity cup.

The above product may be subjected to deep freezing for 24 hours down toa temperature of minus 20 degrees F. and allowed to come back to roomtemperature in another 24 hours and this cycle repeated for 4 or moretimes without deterioration of the emulsion system.

The resulting paint has excellent brushing characteristics and anexceptional wet edge. After drying for 24 hours, the paint film may bewashed without removal of the film.

Example III This example was made similarly to Example H, with theexception that 200 pounds of titanium dioxide constituted the entirepigment employed. In other words, no titanium-calcium pigment nor inertpigment was used. In this case, the pigmentary phase constitutes about 6percent of the total volume. The resulting product is possessed of arelatively high sheen. Below this pigment content, the opacity of theresultant film is deficient for practical purposes.

Example IV Same as Example II, except 390 pounds of titaniumcalciumpigment, pounds of titanium dioxide pigment and no inert or extenderpigments as such were employed.

The resulting emulsion paint product produced a film which wasrelatively weak due to the high pigmentary content (approximately 17percent by volume of the total paint product). When the pigment volumeof the paint is increased to this level and above, washability falls offand the paint film has a tendency to be removed upon rubbing. Whilepigmentation of this level is possible, it is above a practical range.

9 Example V Same as Example II, except that 6 pounds of medium viscositysodium carboxymethyl cellulose were used in lieu of the 8 pounds inExample II. The resulting product was thin in body and the tendency tosplatter and be ditficult to apply to wall areas objectionable. Whilethe emulsion stability was sufficient to allow application, indicationswere that the paint was approaching the point of diminished stabilityand diminished practicability.

Example VI Same as Example II, except that 10 pounds of a mediumviscosity sodium carboxymethyl cellulose or sodium cellulose glycolatewere used in place of the previous 8 pounds.

The viscosity of the resultant' product was too heavy for easybrushability and resistance of the dried paint film to removal bywashing was noticeably decreased. Using this particular protectivecolloid, a practical maximum useful quantity was found at .this level.

Example VII Same as Example II, except that the emulsifying agent was ofthe general formula where R is an oil-soluble group containing at least8 I carbon atoms and n is a whole number from 6 to 50.

fying agent essential to formulate auseful product as to emulsionstability.

Example VIII Same procedure and quantities of material were used as inExample II, except that 20 pounds of an emulsifying agent having thechemical structure (sold under various trade names, e. g. Emulphor DDT,Igepal CA, Antarox .X-400, Triton X-100, etc.) were used in conjunctionwith 5 pounds of a mono-stearic acid condensate of diethanolamine (-seeU. S. Patent No. 2,089,212).

The resulting emulsion paint had decreased viscosity as compared withthat ofExample II. There was a strong tendency to foaming which was notcontrolled by antifoaming agents, and'the washability of the paint filmof the product made by this example was poorer than that of the productof Example II.

This example serves to demonstrate that the proportion of nonionicagents should not exceed percent of the oil phase, as the quantity ofagent used increases there is introduced increasing weakness in driedfilms of the paint product.

' Example IX Same as Example II, except that 85 poundsof the varnishof'Example I were employed to replace the 95 pounds of Example II. I

'The washability of the resultant film was poorer than in Example II andthere was greater tendency for the so made to drag and, to exhibitexcessive flow after appli-;

cation in a film.

Example X 205 pounds of titanium dioxide pigment surface coated with 1.5percent by weight of aluminum resinate by passage of the pigment andcoating agent through a fluid energy mill were weighed into a pony mixerpan. To the pigment was added 200 pounds of water and the paste allowedto stir for 10 minutes. To this was added slowly over a period of 10minutes a mixture of 112 pounds of an oil-modified alkyd varnishcontaining about 25 percent of phthalic anhydride and 62 percent of soyabean oil having an acid value of 10 and containing percent solids. Uponaddition of the varnish, the pigment transferred to the oil phase.Thereafter 3 pounds of 6 percent cobalt naphthenate and 5 pounds of 24percent lead naphthenate drier-were added to the water-in-oilpigmentin-oil dispersion. After thorough agitation of the resultingpaste, 20 pounds of an octyl phenoxy polyoxyethylene ethanol ofmolecular weight between 600 and 800 and 5 pounds of the condensationproduct of stearic acid (one mole) with two mols of diethanolamine ofnonionic nature were added to the mixture. 10 pounds of sodiumcarboxymethyl cellulose were dissolved in 320 pounds of additional wateralong with 10 pounds of emulsified sulfonated tallow anti-foaming agent.This aqueous mixture was thereafter added slowly to the paste underagitation to produce an oil-in-water pigment-in-oil emulsion systemwhich produced a film upon application having a higher degree of glossthan that which was obtained in Example III by dispersion of theuntreated pigment in the aqueous phase.

Example Xl Same as Example II except the 8 pounds of sodium celluloseglycolate (sodium carboxymethyl cellulose) were substituted for with anequal quantity of a medium viscosity sodium cellulose sulfate, e. g., of300-1000 cps.

The resulting paint had good brushing qualities and practicallyequivalent washability to the paint of Example II after 24 hours of dry.

Example XII Same as Example II with the substitution of 10 pounds ofmedium viscosity water soluble methyl cellulose for the 8 pounds ofsodium carboxymethyl cellulose of Example II.

The resulting emulsion paint was useful, but slightly poorer in emulsionstability and inferior in brushing characteristics as compared with theproduct of Example II.

Example XIII Same as Example II with the substitution of a water solubleethyl cellulose of medium viscosity containing between 1.1 and 1.3ethoxy groups per anhydroglucose unit.

The resulting emulsion paint was useful but slightly inferior in qualityto the product of Example II.

Example XIV A series of nonionic surface active agents was selected fromthose commercially available. These were substituted for on equivalentweight basis for the first nonionic agent used in Example II, e. g., thecondensation product of an 8-24 carbon atom alkyl polyethylene glycolcondensation product described in U. S. 1,970.578.

1 The trade names of the general composition of the productssubstitutedwere as follows:

'12 but from 0.9 to 2.0 percent byweight of the said aqueous phase ofsodium carboxymethyl cellulose has provcn TABLE I Trade Name GeneralChemical Structure Remarks Antarox A400 Alkyl aryl polyethylene glycolof the structure Slight drag on brushing.

( i 2H40hoOH2OH2OH OaHio Napacol IL Dlmethylene glycol monolaurate Poorlapping characteriscs. Igepel CO Alkyl aryl polyethylene glycol etherctfinparable to Example (?2H40)9CH2CH:OH

OsHn

Etholat 242/20 Fatty acid rosin acid ethylene oxide condensate Slightdrag on brushing.

(70% rosin acids, 30% ethylene oxide). Ethoiat 242/25 Fatty acid rosinacid ethylene oxide condensate Poor brushing characteris- (HighPrethylene oxide content than 242/20) tics. Emcol H72 Fatty acidcondensation product of a polyhydric Poor wet ed e-EmulsiOn cohol.stability y fair. 7 Triton X-100 Alkyl aryl polyether alcoholPractically equivalent to Example II. lhfilohoHaoHzOfi CgHi Example XVThe following range of proportions is illustrative of practicallimitation of the various components useful to produce a water-reducibleemulsion paint. The limitatations in proportion are not sharp orcritical, however.

From the foregoing illustrative examples and other examples superfluousto include here, it has been found that the useful range of componentsconsists of from 10 to percent by volume of the disperse oleoresinousphase which includes minor quantities of driers, solvents, etc. Theuseful range of pigmentation, based on volume, is from 5 to percent ofthe total volume of the coating and the aqueous phase (includingnonionic agents and protective colloids) accounts for the remaining topercent of the volume.

The amount of nonionic emulsifier essential is based upon the weight ofdisperse oleoresinous phase, and constitutes from 15 to 30% of the oilphase and preferably from 20 to 25 percent thereof.

More than 3 percent of the water soluble cellulose protective colloid byweight of the aqueous phase interferes with good wash fastness of thefilm and is excessive,

satisfactory. 1.0 to 1.5 percent by weight of sodium carboxymethylcellulose is the preferred protective colloid, based on the weight ofthe aqueous phase. By the term medium viscosity is intended theintermediate viscosity grades as furnished by the manufacturers of thewater soluble cellulose derivatives of the class described.

It is pointed out for purposes of explanation that the range ofpercentages as described herein is not critical in the sense that up toan exact figure the composition works very well and beyond that thesystem is inoperative, but rather that the range illustrated representsthat range most practically useful for the purposes of the invention.Determination of useful and optimum ranges has been established by manytrial batches. It has been found by experience that desired qualities ofemulsion paint products are diminished rapidly as the stated usefulranges are exceeded. Illustrative of this is the increase in amount ofnonionic surface active agent beyond the stated range; when this isdone, the paint film becomes readily removable when washed. If theamount is less than the stated range, creaming and emulsion instabilityproblems become a source of serious complaint.

increasing the volume of the oil phase (varnish) in proportions outsidethe stated range also creates formulation unbalance with consequentstrong tendency to high viscosity products, sticky brushing characterand excessive flow. Decreasing the volume of the disperse oleoresinousphase to less than the stated range develops a product characterized bypoor Washability and ready removal in the presence of soap and water.

Having described my improved emulsion paint in such wise as to be easilyduplicated by one skilled in the art, I claim:

1. An emulsion coating composition characterized by its capacity totolerate calcium sulfate ions without 13 emulsion break-down uponapplication consisting of a continuous aqueous phase, a discontinuousoil phase and a pigmentary solid phase; said aqueous phase consistingessentially of a fiuid colloidal solution of water soluble cellulosederivatives characterized by their aqueous gel forming quality at lowsolids concentrations and at least one salt-free organic nonionicdetergent of molecular weight above 550 containing a plurality ofoxyalkylene units of not more than 3 carbon atoms each and a hydrophobicorganic group containing at least 8 carbon atoms wherein said oil phaseconsists essentially of a non-volatile oleoresinous varnish vehicle oflow acid value and said pigmentary phase comprises calcium sulfatecontaining pigment.

2. An emulsion coating composition characterized by its capacity totolerate calcium sulfate ions without emulsion break-down uponapplication consisting of a continuous aqueous phase, a discontinuousoil phase and a pigmentary solid phase; said aqueous phase consistingessentially of a fluid colloidal solution of water soluble cellulosederivatives characterized by their aqueous gel forming quality at lowsolids concentrations and at least one salt-free organic nonionicdetergent selected from the group consisting of the condensationproducts of a water insoluble ester, ether, 'amine and amide of amonomeric organic compound containing a hydrophobic and oilophilic groupof at least eight carbon atoms in size with a suflicient number ofoxyalkylene units containing not more than three carbon atoms each and ahydrophobic organic group containing at least 8 carbon atoms to producea water soluble product having a molecular weight in excess of 550, andsaid oil phase consisting essentially of a non-volatile oleoresinousvarnish vehicle of acid value less than about 20 and said pigmentaryphase comprises calcium sulfate containing pigment.

3. A pigmented emulsion coating composition characterized by itscapacity to tolerate calcium sulfate containing pigments in thepigmentary phase, a continuous aqueous phase consisting essentially of afluid colloidal solution of water soluble cellulose derivativescharacterized by their aqueous gel forming quality at low solidsconcentrations and a salt-free organic nonionic detergent having amolecular weight of at least 550 and a ratio of molecular weight ofhydrophilic groups to molecular weight of hydrophobic and oilophilicgroups in the said molecule of nonionic agent within the range of from1.5 to 1 to about 3 to 1, and a disperse oil phase comprising anon-volatile oleoresinous varnish vehicle of acid value of not more thanabout 20 and said pigmentary phase comprises calcium sulfate containingpigment.

4. As in claim 3, wherein the water soluble cellulose is an alkali metalsalt of carboxymethyl cellulose.

5. As in claim 3, wherein the salt-free nonionic detergent is an alkylphenoxy polyoxalkylene ethanol wherein the oxyalkylene groups containnot more than three carbon atoms, and the alkyl group contains at least2 carbon atoms, and the molecular weight of the nonionic detergent isabove 600.

6. As in claim 3, wherein the nonionic detergent is a C8 to C9 alkylphenoxy polyoxyethylene ethanol, the oxyethylene units number from 8 to12 and the molecular weight of the said surface active agent is withinthe limits of 600-800.

7. As in claim 3, wherein the water soluble cellulose is sodiumcarboxymethyl cellulose and the nonionic detergent is a Ca to C9 alkylphenoxy polyoxyethylene ethanol, the oxyethylene units number from 8 to12 and the molecular weight of the said surface active agent is withinthe limits of 600-800.

8. As in claim 3, wherein the water soluble cellulose is sodiumcarboxymethyl cellulose and the nonionic detergent is an octyl phenoxypolyoxyethylene ethanol of 14 molecular weight not less than 600 orrnorethan about 9. A pigmented emulsion composition characterized by itscapacity to tolerate calcium sulfate containing pigments in thepigmentary phase without emulsion breakdown upon application of saidcoating consisting of from 5 to 20%. by volume of pigmentary phase, from60 to 75% by volume of a continuous aqueous phase and from 10 to 15% byvolume 'ofiaidispe'r'sed oil phase, said aqueous phase consistingessentially; of from 0.9 to 3l0 pe rcent by"wight"thereof of watersoluble 'eeuulose derivatives characterized by their aqueous gel formingquality at low solids concentrations ether and from 10 to 30% by weightbased on said oil phase of' a saltfree nonionic detergent selected fromthe group consisting of the condensation products of a water insolubleester, ether, amine and amide of a monomeric organic compound containinga hydrophobic and oilophilic group of at least eight carbon atoms insize condensed with a suflicient number of alkylene oxide unitscontaining not more than three carbon atoms each to produce a watersoluble product having a molecular weight in excess of 550, and said oilphase comprising a non-volatile oleoresinous varnish vehicle of acidvalue less than about 20 and said pigmentary phase comprises calciumsulfate containing pigment.

10. A pigmented emulsion coating composition characterized by itscapacity to tolerate calcium sulfate containing pigments in thepigmentary phase without emulsion breakdown upon application of saidcoating consisting of from 5 to 20% by volume of pigmentary phase, from60 to 75% by volume of a continuous aqueous phase and from 10 to 15% byvolume of a dispersed oil phase, said aqueous phase consistingessentially of from 0.9 to 3.0 percent by weight thereof of watersoluble cellulose derivatives characterized by their aqueous gel formingquality at low solids concentrations ether and from 10 to 30% by weightbased on said oil phase of a salt-free nonionic detergent selected fromthe group consisting of the condensation products of a water insolubleester, ether, amine and amide of a monomeric organic compound containinga hydrophobic and oilophilic group of at least eight carbon atoms insize condensed with a suflicient number of alkylene oxide unitscontaining not more than three carbon atoms each to produce a watersoluble product having a molecular weight in excess of 550 and a ratioof molecular weight of hydrophilic groups to molecular weight ofhydrophobic groups in said nonionic agent within the range of from 1.5to 1 to 3 to l, and said oil phase comprising a non-volatileoleoresinous varnish vehicle of acid value less than about 20 and saidpigmentary phase comprises calcium sulfate containing pigment.

11. As in claim 10, wherein the water soluble cellulose is an alkalimetal salt of carboxymethyl cellulose and the quantity used is from 1.0to 1.5% by weight of the aqueous phase.

12. As in claim 10, wherein the nonionic detergent is an alkyl phenoxypolyoxyalkylene ethanol, the alkyl group contains at least 2 carbonatoms, the oxyalkylene groups containing not more than three carbonatoms per unit and the molecular weight of the nonionic detergent is notless than 600.

13. As in claim 11, wherein the nonionic detergent is an alkyl phenoxypolyoxyalkylene ethanol, the alkyl group contains at least 2 carbonatoms, the oxyalkylene groups containing not more than three carbonatoms per unit, the molecular weight of the nonionic detergent is notless than 600 and the water soluble cellulose is an alkali metal salt ofcarboxymethyl cellulose.

14. As in claim 1 where the water soluble cellulose derivative is methylcellulose.

15. As in claim 1 where the water soluble cellulose derivative is watersoluble ethyl cellulose.

16. As in claim 1 where the water soluble cellulose derivative ishydroxyethyl cellulose.

17. As in claim 1 where the Water soluble cellulose derivative is sodiumc'arboxymethyl cellulose.

18. As in claim 1 Where the Water soluble cellulose 5 derivative issodium cellulose sulfate.

References Cited in the file of this patent 15 Bacon et a1 June 8, 1943Kli kenstein Dec. 14, 1943 Hofimann Feb. 22, 1944 Auer- Aug. 14, 1945Watters Apr. 24, 1951 Marberg et a1 Sept. 11, 1951 Maxcy et al. Jan. 6,1953

1. AN EMULSION COATING COMPOSITION CHARACTERIZED BY ITS CAPACITY TOTOLERATE CALCIUM SULFATE IONS WITHOUT EMULSION BREAK-DOWN UPONAPPLICATION CONSISTING OF A CONTINUOUS AQUEOUS PHASE, A DISCONTINUOUSOIL PHASE AND A PIMENTARY SOLID PHASE; SAID AQUEOUS PHASE CONSISTINGESSENTIALLY OF A FLUID COLOIDAL SOLUTION OF WATER SOLUBLE CELLULOSEDERIVATIVES CHARACTERIZED BY THEIR AQUEOUS GEL FORMING QUALITY AT LOWSOLIDS CONCENTRATIONS AN AT LEAST ONE SALT-FREE ORGANIC NONIONICDETERGENT OF MOLECULAR WEIGHT ABOVE 550 CONTAINING A PLURALITY OFOXYALKYLENE UNITS OF NOT MORE THAN 3 CARBON ATOMS ECH AND A HYDROPHOBOCORGANIC GROUP CONTAINING AT LEAST 8 CARBON ATOMS WHEREIN SAID OIL PHASECONSISTS ESSENTIALLY OF A NON-VOLATILE OLEORESINOUS VARNISH VEHICLE OFLOW ACID VALUE AND SAID PIGMENTARY PHASE COMPRISES CALCIUM SULFATECONTAINING PIGMENT.